1. Technical Field
Example embodiments of the present invention relate to a wireless LAN technology, and more specifically, relate to channel sounding and scheduling technologies for interference alignment.
2. Related Art
A variety of wireless communication technologies have been developed with the development of information and communication technology. Among them, a wireless local area network (WLAN) is a technology that enables wireless access to the Internet in home, a company or a specific service area using a portable terminal such as a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), a smart phone, or a tablet PC based on a radio frequency technology.
A standard of the wireless LAN technology is developed as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. A wireless LAN technology according to the IEEE 802.11a standard operates based on an orthogonal frequency division multiplexing (OFDM) scheme, and may provide a transmission rate of up to 54 Mbps in a 5 GHz band. A wireless LAN technology according to the IEEE 802.11b standard operates based on a direct sequence spread spectrum (DSSS) scheme and may provide a transmission rate of up to 11 Mbps in a 2.4 GHz band. A wireless LAN technology according to the IEEE 802.11g standard operates based on an OFDM scheme or a DSSS scheme and may provide a transmission rate of up to 54 Mbps in a 2.4 GHz band.
A wireless LAN technology according to the IEEE 802.11n standard operates in a 2.4 GHz band and a 5 GHz band based on an OFDM scheme. When a multiple input multiple output-OFDM (MIMO-OFDM) scheme is used, a transmission rate of a maximum of 300 Mbps can be provided for four spatial streams. The wireless LAN technology according to the IEEE 802.11n standard may support a channel bandwidth up to 40 MHz. In this case, a transmission rate of a maximum of 600 Mbps can be provided.
As the spread of such a wireless LAN is activated and applications using this are diversified, there is an increasing need for a new wireless LAN technology for supporting a higher throughput than a data transaction rate supported by IEEE 802.11n. A very high throughput (VHT) wireless LAN technology is one of IEEE 802.11 wireless LAN technologies proposed to support a data transaction rate of 1 Gbps or more. Among them, IEEE 802.11ac is developed as a standard for providing a very high throughput in a band of 5 GHz or less, and IEEE 802.11ad is developed as a standard for providing a very high throughput in a 60 GHz band.
A plurality of basic service sets (BSSs) are highly likely to be overlapped and interfered with each other as use of the wireless LAN recently increases. Accordingly, communication performance may be degraded in an overlapped basic service set (OBSS).